Induction of gynogenesis in red bighead carp (Aristichthys nobilis red var.)

Gynogenesis was induced in red bighead carp(Aristichthys nobilis red var.)eggs using the UV-irradiated diploid sperm of allotetraploid hybrids,which were derived from crossing of red crucian carp(♀)×common carp(♂),with cold shock treatment in 4-6 ℃ water for 11-13 min to make chromosome doubled.Different initiation time of treatments resulted in two types of diploid gynogenetic red bighead carp:meiotic gynogenetic(meiG)and mitotic gynogenetic(mitG).The survival rates of meiG and mitG were 19.4%±2.3%,7.3%±1.9% respectively.The gynogenetic fish were confirmed by morphological characteristics,chromosome counting,and microsatellite DNA analysis.The results showed that both meiG and mitG gynogenetic fish were identified as diploid with 48 chromosomes,which produed exclusively bands being same as that in maternal parents and discriminated from that in allotetraploid hybrids by microsatellite DNA analysis.All the gynogenetic fish were female,89% of which showed normal ovary development.It provided important data for suggesting XX genotype in female red bighead carp.In addition,the body color of gynogenesis offspring(gynogenetic red bighead carp(♀)×wild red bighead carp(♂))was redder than that in wild red bighead carp.The formation of gynogenetic red bighead carp should be a valuable contribution to body color non-degradation,genetic improvement in fish breeding,as well as sex determination researches in fish.